Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy: A 16-Year Australian Single Centre Experience

Background: Alcohol septal ablation (ASA), is a well-established treatment for symptomatic hypertrophic obstructive cardiomyopathy (HOCM). We report the acute, short and long-term clinical and echocardiographic outcomes of our experience in a single Australian centre over 16 years.

Methods: We retrospectively analysed consecutive patients presenting to our centre for ASA between March 2000 and July 2016. Local databases were interrogated along with direct patient or physician contact occurred where required.

Results: Alcohol septal ablation was performed in 80 patients with symptomatic, medication refractory HOCM (mean age 61±15 years; range 22-84 years; 50% male). All patients had transthoracic echocardiography prior to the procedure, within 48hours of the procedure, 6 weeks, 6 months, 1 year and yearly thereafter to a median follow-up of 80±40months. At baseline, mean resting and provoked LVOT gradients were 80±49mmHg and 97±40mmHg respectively. Compared with baseline, ASA led to a reduction in resting LVOT gradients at all time points, particularly at 2 days-52±41mmHg, p<0.001; 12 months-29±34mmHg, p<0.001; and last follow-up 12±21mmHg, p<0.001. Provoked LVOT gradients were also reduced at 2 days-64±44mmHg and last follow-up of 19±29mmHg, p<0.001. Compared to baseline (19.8±4.2mm), ASA was associated with a reduction in interventricular septal (IVS) thickness at all time intervals with last echocardiographic follow-up at 80 months being 16.0±4.9mm, (<p=0.001). The incidence of new RBBB was 27% and pacemakers were inserted in 24% of patients due to complete heart block. There was 1 (1.1%) in hospital death. At last clinical follow-up at 93 months (IQR 86-100) there was a significant reduction in mean NYHA class from 2.5 to 1.1 (p=<0.05) and reduction in the incidence of pre-syncope of 23% vs 3% (p=0.005).

Conclusions: In correctly selected patients, ASA is a safe and efficacious procedure resulting in significant reduction of LVOT gradient, clinical symptoms and IVS thickness. The largest effect occurs in the first year post procedure, however ongoing decrease of LVOT gradient and symptoms can be seen many years post ablation.